SCAEY-FC-R410A scroll compressors

GENERALThe SCAE-FC free-cooling units are particularly suitable where chilled water all year long is required, so also by low ambient air temperature. The free-cooling system utilises the low outside temperature for chilling water in the coilstarting from 15°C ambient air temperature.

THE FREE-COOLING PRINCIPLEThe units series SCAEY-FC are designed to cool down water/glycol fluid. This units are equipped, further to the chiller components such as compressors, condensers, evaporator, thermostatic valves, with a water free-cooling coil. The control system consists of a modulating three-way valve and of a certain number of probes allowing the water coil functioning and therefore the “free-cooling” operation. In the standard chiller the return water/glycol fluid is cooled down through the shell and tube evaporator. In the SCAEY-FC units working in free-cooling mode, the water/glycol fluid runs through the free-cooling coil which is cooled by means of the external air, thus reducing the load on the compressors or even completely substituting them. The control system consists of a microprocessor, an inlet water temperature probe, an external air temperature probe, a working probe and a nofreezing probe.

OPERATION IN SUMMERWhen the ambient air temperature is higher than the return water/glycol temperature the cooling capacity is guaranteed by the compressors; the 3-way valve allows the water/ glycol to go into the evaporator (12); the free-cooling coil (11) is not working. The absorbed power is the same as a traditional electric air cooled chiller.

OPERATION IN WINTERWhen the ambient air temperature is lower 3-0°C, the chiller operates in free cooling mode: the 3-way valve (9) allows the water/glycol to go into the free-cooling coil (11), the probe (5) switch off the compressors (10). The fans (13) keep woring to guarantee the air flow through the free-cooling coil (11). By the external air decreasing, the microprocessor (15) activates by reaching the set point the fans switch off.

OPERATION IN MID SEASONIt’s a combination of free-cooling and traditional electric chiller. The free-cooling operation starts when the external air temperature is at least 2°C lower than the return liquid temperature; so, normally at 15-10°C. The liquid is pre-cooled in the free-cooling coil (11). The performance is completed by the compressors. The water temperature probe (5) controls the compressor (10)capacity steps.

BENEFITS• Your overheads would reduce in the mid season.• Your free cooling system could run automatically whenrequired.• There would be less wear and tear due to the reducedhours of operation.• Your maintenance costs would reduce